[BUG]: RabbitMQ Basic Properties overwritten to default values

[johang88]

Tracer Version(s)

3.11.1

Operating system and platform

Linux

Instrumentation Mode

manual with nuget package

TFM

net9.0

Bug Report

If BasicPublishAsync is called with a writable BasicProperties then PopulateBasicPropertiesHeaders in rabbitmq-dotnet-client will return null as no new object is created. In turn the instrumentation code will get a return value of null and create a new basic properties object resulting in all values having default values instead of the ones set by the caller.

Implementation in rabbitmq-dotnet-client: https://github.com/rabbitmq/rabbitmq-dotnet-client/blob/85fd42fc6e245dc68901802967acbccc216b5980/projects/RabbitMQ.Client/Impl/Channel.BasicPublish.cs#L190

Implementation in dd-trace:

dd-trace-dotnet/tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/RabbitMQ/PopulateBasicPropertiesHeadersIntegration.cs

Line 48 in f5e1c39

returnValue ??= CachedBasicPropertiesHelper<TReturn>.CreateHeaders();

Reproduction Code

No response

[johang88]

Extra context showing the null handling of the return value from https://github.com/rabbitmq/rabbitmq-dotnet-client/blob/85fd42fc6e245dc68901802967acbccc216b5980/projects/RabbitMQ.Client/Impl/Channel.BasicPublish.cs#L75

As can be seen it will use the returned props if not null then they will be used instead of the supplied props object.